It has proved that operators working in process plants, such as factories, electric utilities and the like, prefer to carry out their work with the aid of older types of control equipment, instrument and control panels rather than the more modern display screens.
One disadvantage of the older type of control equipment is the significantly lower flexibility. Instruments and control buttons cannot, of course, be readily replaced or moved about on the control panel, among other things because of the extensive wiring that this would require. This entails considerable drawbacks when the controlled processes are changed, updated or replaced. Currently, supervision and control are therefore carried out to an increasing extent with the aid of display screens, the interfaces of which may be readily adjusted to different purposes and needs. The contents of the display screens are, of course, controlled by the processes in a computer.